Basics of Biology

Biology and Life

What did scientists eventually discover about Miller’s experiment?

After Stanley Miller died in 2007, scientists who inherited the original experiment looked even closer at Miller and Urey’s results—thanks to advances in analytical tools. They found that far more organic molecules existed than Miller reported, with fourteen amino acids and five amines (a class of organic compounds derived from ammonia). The scientists also uncovered two additional experiments that were never published. One produced a lower diversity of organic molecules, while the other produced a much wider variety. In the latter experiment, Miller included conditions similar to those of volcanic eruptions—something that scientists believe was quite prevalent on the early Earth— with the experiment producing twenty-two amino acids, five amines, and many hydroxylated molecules. These and other experiments suggest that the early Earth’s volcanic activity may have been instrumental in producing the precursors to life.